JP2023087547A - Bonding wire and semiconductor device - Google Patents

Abstract

To provide a bonding wire superior in long-term reliability, which can achieve a satisfactory circular form as to FAB shape when FAB is put in contact with an electrode and crushed.SOLUTION: In a semiconductor device M, a bonding wire W comprises: 0.005 mass% or more and 2.0 mass% or less of In; one or two elements selected from Au and Pd where the total content is 0.005 mass% or more and 2.0 mass% or less; one or more elements selected from Bi and Cu, where the total content is 5 mass ppm or more and 500 mass ppm or less; one or more elements selected from a group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce, where the total content is 0 mass ppm or more and 500 mass ppm or less; and the balance consisting of Ag.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bonding wire and a semiconductor device containing Ag (silver) as a main component.

2. Description of the Related Art Bonding wires used for connecting electrodes on a semiconductor element and electrodes on a substrate are generally very thin and are therefore manufactured from metal materials with good conductivity and excellent workability. In particular, bonding wires containing Au (gold) as a main component have been widely used conventionally because of their chemical stability and ease of handling in the atmosphere. However, bonding wires containing Au as a main component are very expensive because 99% or more of the mass is Au.

Therefore, a bonding wire whose main component is Ag (silver) has also been proposed. Ag is less expensive than Au, but a bonding wire containing Ag as a main component is inferior in long-term reliability and resistance to changes in ambient temperature (heat cycle property). In order to solve this problem, as in Patent Document 1 below, elements such as In (indium), Ga (gallium), and Cd (cadmium) are added to Ag as a main component to improve long-term reliability. is proposed.

By the way, in ball bonding, a free air ball (hereinafter abbreviated as FAB) formed at the tip of a bonding wire by discharge heating or the like is pressed against an electrode and crushed, and then thermal energy and vibration energy are applied to perform 1st bonding. . After the 1st bonding, the outer peripheral surface of the bonding wire is pressed against the other electrode to perform the 2nd bonding. With the recent increase in the density of semiconductor devices, fine pitch electrodes are progressing. It is required to prevent short circuits. However, the bonding wire of Patent Literature 1 below has a problem that it is difficult to control the shape of the 1st joint portion and it is difficult to cope with fine pitch.

Patent No. 6207793

The present invention has been made in view of the above circumstances, and a bonding wire containing Ag as a main component has good long-term reliability and a good circular shape when FAB is brought into contact with an electrode and crushed. An object of the present invention is to provide a bonding wire capable of

In order to solve the above problems, the bonding wire of the present invention has an In content of 0.005% by mass or more and 2.0% by mass or less, and a content of one or two elements selected from Au and Pd. A total of 0.005% by mass or more and 2.0% by mass or less, a total content of one or more elements selected from Bi and Cu of 5 mass ppm or more and 500 mass ppm or less, Ca, Mg, Ge , Y, Nd, Sm, Gd, La and Ce. is.

In the bonding wire according to the present invention, the total content of one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce is 10 ppm by mass or more. It can be 500 mass ppm or less.

In the bonding wire according to the present invention, the ratio of the In content to the total content of Au and Pd can be 5 or less.

The bonding wire according to the present invention can contain both elements of Bi and Cu.
In the bonding wire according to the present invention, the HAZ length generated when fabricating a FAB having a size 2.0 times as large as the wire diameter of a wire having a wire diameter of 25 μm in a nitrogen gas atmosphere can be 100 μm or less.

In the bonding wire according to the present invention, the average grain size in the area up to 30% of the wire diameter in the radial direction from the wire surface with respect to the average grain size in the area up to 30% of the wire diameter in the radial direction centering on the wire center The diameter ratio can be 0.5 or more and 5.0 or less.

In the bonding wire according to the present invention, if a crystal that exists in the center of the wire and has a ratio of the length in the wire radial direction to the length in the wire longitudinal direction of 1/10 or less is an elongated crystal grain, the wire center is included The ratio of the area of the elongated crystal grains to the cross section in the longitudinal direction of the wire can be 40% or less.

A semiconductor device of the present invention is a semiconductor device using the bonding wire according to any one of the above-described present inventions.

The bonding wire containing Ag as the main component of the present invention can have good long-term reliability and a good circular shape of the 1st joint formed when the FAB is brought into contact with the electrode and crushed.

2 is an enlarged view of a wire W connecting electrodes in a semiconductor device; FIG. FIG. 4 is a SEM image of a cross section in the longitudinal direction including the wire center of the bonding wire of the present embodiment, and is a diagram for explaining a method of calculating the average crystal grain size ratio. It is a SEM image of a cross section in the longitudinal direction including the wire center of the bonding wire of the present embodiment, and is a diagram for explaining a method of calculating the ratio of the area of elongated crystal grains in the cross section in the wire longitudinal direction including the wire center. be. Enlarged view of flat-bonded bonding wire

A bonding wire W and a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings.

The semiconductor device M exemplified in FIG. 1 is, for example, power IC, LSI, transistor, BGA (Ball Grid Array package), QFN (Quad Flat Non lead package), LED (light emitting diode), or other semiconductor element 1 electrodes (e.g. , Al alloy electrodes, nickel/palladium/gold-coated electrodes, Au-coated electrodes, etc.) 10 and conductor wiring (electrodes) 11 of the circuit wiring board (lead frame, ceramic substrate, printed circuit board, etc.) 2 connect the bonding wires W. It is connected by the ball bonding method used.

The bonding wire W used in the semiconductor device M is selected from the group consisting of 0.005% by mass or more and 2.0% by mass or less of In, and 0.005% by mass or more and 2.0% by mass or less of Au and Pd (palladium). Contains one or two selected elements and one or two elements selected from the group consisting of 5 ppm by mass or more and 500 mass ppm or less of Bi (bismuth) and Cu (copper), and the balance consists of Ag.

The wire diameter of the bonding wire W may be varied depending on the application. For example, the wire diameter of the bonding wire W can be 5 μm or more and 150 μm or less.

Specifically, Ag constituting the bonding wire W may contain impurities such as iron (Fe) that inevitably exist in terms of refining. It is preferable to fabricate an Ag alloy that constitutes

Since the bonding wire W contains In, the corrosion resistance of the 1st joint 12 formed on the electrode 10 is improved by crimping the melted FAB to the electrode 10, and the long-term reliability can be improved. Electrodes of semiconductor packages are often coated with Al (aluminum) or an Al alloy. When Ag and Al are joined, an intermetallic compound layer of Ag and Al such as Ag ₂ Al or Ag ₃ Al is generated at the joint interface. The intermetallic compound layer formed on the joint interface is likely to deteriorate the 1st joint portion 12 due to entry of water or chlorine from the outside. When the bonding wire contains a certain amount of In, deterioration of the Ag-Al intermetallic compound layer due to water or chlorine entering from the bonding interface can be suppressed, and the corrosion resistance of the 1st bonding portion 12 can be improved.

When the In content is 0.005% by mass or more, the corrosion resistance of the 1st joint 12 is improved, and long-term reliability can be improved. When the In content is 2.0% by mass or less, the specific resistance of the wire is maintained within an appropriate range. Further, when the In content is 2.0% by mass or less, the loop shape formed when the electrodes 10 and 11 are connected is less likely to vary.

By containing at least one element of Au and Pd, the bonding wire W can improve the corrosion resistance of the 1st joint 12 and improve the long-term reliability. In particular, by containing at least one element of Au and Pd in addition to In, the corrosion resistance of the 1st joint 12 is remarkably improved while the specific resistance of the bonding wire W is suppressed, and the long-term reliability is greatly improved. can do. Also, by containing at least one element of Au and Pd, the loop height H (see FIG. 1) formed when the electrodes 10 and 11 are connected can be reduced.

The total content of one or two elements selected from Au and Pd is preferably 0.005% by mass or more and 2.0% by mass or less. When it is 0.005% by mass or more, long-term reliability can be improved and the loop height H can be reduced. When the total content of Au and Pd is 2.0% by mass or less, the noble metal content is low and the manufacturing cost of the bonding wire can be suppressed.

In particular, from the point of view of improving the long-term reliability while suppressing the specific resistance of the bonding wire W, Au, It preferably contains Pd and In, more preferably 1 or more and 3 or less.

Since the bonding wire W contains at least one of Bi and Cu, the shape of the 1st joint portion 12 can be controlled to be nearly circular. The total content of Bi and Cu is preferably from 5 ppm by mass to 500 ppm by mass, more preferably from 5 ppm by mass to 100 ppm by mass, and even more preferably from 5 ppm by mass to 50 ppm by mass.

Even if each of Bi and Cu is added alone, the effect of controlling the shape of the 1st joint 12 to a shape close to a circle can be obtained. The grains are more aligned and the shape is closer to a circle. If more Bi is added than Cu, it is possible to suppress the occurrence of unevenness and shrinkage cavities on the surface of the FAB, so it is more preferable to contain more Bi than Cu.

In the present invention, in addition to the above-described Au, Pd, In, Bi and Cu, a group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce (hereinafter referred to as "selective element group" may additionally contain one or more elements selected from That is, the selected element group is an arbitrary component. If the total content of the selective element group is 500 ppm by mass or less, the above-described effects obtained by adding Au, Pd, In, Bi and Cu are not impaired. In addition, when the total content of the selected element group is 10 ppm by mass or more, the heat resistance of the wire is improved, and a large region of crystal grains called HAZ (Heat Affected Zone) is less likely to occur during FAB formation. can reduce the height H of the loop of Therefore, when the selected element group is added, the total content of the selected element group is preferably 10 mass ppm or more and 500 mass ppm or less, more preferably 10 mass ppm or more and 100 mass ppm or less.

Moreover, when adding a selective element group, it is preferable that the total content of the selective element group is larger than the total content of Bi and Cu. By containing more elements selected from the selected element group than Bi and Cu, the loop height H can be reduced without deteriorating the sphericity of the FAB shape.

Next, the rod-shaped ingot is drawn to reduce its diameter until it reaches a predetermined diameter, thereby forming a bonding wire. Note that a softening heat treatment may be performed during wire drawing, if necessary.

After wire drawing to a predetermined diameter, if necessary, the wire is run in a heat treatment furnace for refining heat treatment to obtain a bonding wire.

The bonding wire of the present embodiment has an In content of 0.005% by mass or more and 2.0% by mass or less, and a total content of one or two elements selected from Au and Pd of 0.005% by mass. % or more and 2.0 mass % or less, the total content of one or more elements selected from Bi and Cu is 5 mass ppm or more and 500 mass ppm or less, and the balance is Ag, so long-term reliability In addition to improving the resistance and heat cycle property, the height of the loop formed during connection can be reduced, the stability of the loop shape can be improved, and the stability of the shape of the joint with the electrode can be improved.

The bonding wire W of the present embodiment may additionally contain one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce. , the total content of these elements is preferably 10 ppm by mass or more and 500 ppm by mass or less. In addition to Au, Pd, In, Bi and Cu, additionally one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce By containing it, the strength and heat resistance of the wire can be increased, and the heat cycle property can be improved.

In addition, in the bonding wire of this embodiment, the HAZ length generated when fabricating a FAB having a diameter 2.0 times as large as the wire diameter in a nitrogen gas atmosphere can be 100 μm or less. With such a length, the height of the loop formed at the time of wire connection can be reduced, and the thickness of the semiconductor device can be reduced.

The HAZ length can be measured by observing the appearance of the bonding wire using a general-purpose electron microscope.

In addition, in the bonding wire of the present embodiment, in the SEM image of the cross section in the longitudinal direction including the wire center C of the bonding wire as shown in FIG. (Regions up to 15% of the wire diameter on both sides in the radial direction across the wire center C) The average crystal grain size in the region R2 up to 30% of the wire diameter in the radial direction from the wire surface with respect to the average crystal grain size D1 in R1 A ratio P (=D2/D1) of D2 can be set to 0.5 or more and 5.0 or less. In such a case, the shape of the 1st joint 12 formed when the FAB is pressed and crushed against the electrode can be controlled to be nearly circular.

In addition, the average crystal grain size in this specification can be calculated|required by following formula (1).

In formula (1), N arbitrarily selects a region with a length of 3 to 4 times the wire diameter in the longitudinal direction of the wire from the cross-sectional SEM image of the bonding wire as shown in FIG. It is the number of existing crystal grains. S is the area of the region selected as above.

In the bonding wire according to the present invention, if a crystal that exists in the center of the wire and has a ratio of the length in the wire radial direction to the length in the wire longitudinal direction of 1/10 or less is an elongated crystal grain, it is shown in FIG. The ratio Q of the total area of the elongated crystal grains in the cross section in the longitudinal direction of the wire including the wire center C (in the case of FIG. 3, corresponds to the area of the region R3 composed of the elongated crystal grains present in the center of the wire) It can be 40% or less. In such a case, loop shape stability can be enhanced.

In addition, the bonding wire W of this embodiment can be used as a bonding wire for various aspects other than the semiconductor device as described above.

Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Ag raw materials having a purity of 99.9% by mass or more were used to melt Ag alloys having compositions as shown in Table 1 below, and rod-shaped ingots were produced by continuous casting. The produced rod-shaped ingots were subjected to wire drawing to reduce the diameter to reach 25 μm, and then subjected to refining heat treatment to obtain bonding wires of Examples 1 to 11 and Comparative Examples 1 to 7. The wire diameters (diameters) of the bonding wires of Examples 1 to 11 and Comparative Examples 1 to 7 are all 25 μm.

The obtained bonding wires of Examples 1 to 11 and Comparative Examples 1 to 7 were evaluated for the following (1) to (11). Specific evaluation methods are as follows.

(1) Specific Resistance Three samples for evaluation were prepared for each bonding wire of Examples 1 to 11 and Comparative Examples 1 to 7, and electrical resistance at room temperature was measured using a four-probe method. If the average value of the specific resistance of the three evaluation samples is less than 4.0 μΩ·cm, the sample has sufficient conductivity, so it is rated as “A”, and if it is 4.0 μΩ·cm or more, it is rated as “D”.

(2) Loop height Using a wire bonder (wire bonder FB-780, manufactured by Kaijo Co., Ltd.), as shown in FIG. Flat bonding was performed in a nitrogen gas atmosphere so that the height of the joint portion (second joint portion) formed by pressing the outer peripheral surface against the electrode 11 was the same. The height h from the ground point of the 2nd junction to the wire at the highest point was measured using an optical microscope. "A" if the height h is 3 to 5 times the wire diameter, "B" if the height H is 5 to 10 times the wire diameter, and if the height H is 10 times or more the wire diameter "D".

(3) FAB sphericity (formability)
Using the wire bonder used in (2) above, a FAB having a size 1.9 to 2.1 times the diameter of the wire was produced in a nitrogen gas atmosphere. As an evaluation of FAB sphericity (formability), 100 FABs were prepared for each bonding wire of Examples and Comparative Examples, and then examined with a general-purpose electron microscope (manufactured by JEOL Ltd., JSM-6510LA). The appearance was observed, and the lengths of the fabricated FAB in the wire parallel direction and the wire vertical direction were measured. If the average value of the ratio (X/Y) of the length X in the wire parallel direction to the length Y in the vertical direction of the FAB is 85% or more and 115% or less, it is judged to be "spherical" and "A", above. If the average value of the ratio (X/Y) was less than 85% or greater than 115%, or if a circular shape was not visually observed, it was rated as "D".

(4) HAZ length Observe the appearance of the wire from which the FAB was produced in (3) above with the general-purpose electron microscope, measure the length of the HAZ generated in the wire portion near the FAB, and calculate the average value. bottom.
If the HAZ length was 100 μm or less, it was rated “A”, and if it was longer than that, it was rated “B”.

(5) Ratio P of the average crystal grain size in the surface region of the bonding wire to the average crystal grain size in the internal region of the bonding wire
After exposing the cross section of the wire in the longitudinal direction with a cross-section sample preparation device (manufactured by JEOL Ltd., IB-09020CP), a general-purpose electron microscope (manufactured by JEOL Ltd., JSM-6510LA) was used to examine the cross section of the wire. An SEM image of the metallographic structure was acquired, and a region with a length of three times the wire diameter was arbitrarily selected from the acquired SEM image in the longitudinal direction of the wire. For the selected regions, the average grain size D1 in a region R1 of 30% of the wire diameter in the radial direction around the wire center C, and the average grain size in a region R2 of up to 30% of the wire diameter in the radial direction from the wire surface D2 was calculated, and the ratio P of the average crystal grain size D2 in the region R2 to the average crystal grain size D1 in the region R1 was calculated.

The average crystal grain size D1 is obtained by measuring the number N of crystal grains present in the region R1 and the area S of the region R1 over a length three times the wire diameter in the longitudinal direction of the wire from the SEM image, and using the above formula ( 1). The average crystal grain size D2 is obtained by measuring the number N of crystal grains present in the region R2 and the area S of the region R2 over a length three times the wire diameter in the longitudinal direction of the wire from the SEM image, and using the above formula (1). obtained by

When the ratio P of the average crystal grain size D2 in the region R2 to the average crystal grain size D1 in the region R1 was 0.5 or more and 5.0 or less, it was rated as "A", and otherwise as "B".

(6) Ratio Q of the area of elongated crystal grains to the area of the entire wire
From the SEM image of the metal structure obtained by the same method as in (5) above, a region with a length three times the wire diameter is arbitrarily selected in the longitudinal direction of the wire, and the crystal grains present in the selected region are examined in the longitudinal direction of the wire. And the length in the radial direction of the wire was measured, and the ratio of the length in the radial direction of the wire to the length in the longitudinal direction of the wire was calculated. Crystals with a calculated ratio of 1/10 or less were defined as elongated crystal grains, and the total area (total area) of the elongated crystal grains existing in the selected region was measured. Then, the ratio Q of the total area of the elongated crystal grains to the area of the selected region was calculated. "A" was given when the calculated ratio Q was 40% or less, and "B" was given otherwise.

(7) Size stability of 1st joints 100 FABs prepared in a nitrogen gas atmosphere with the wire bonder used in (2) above were pressed against an electrode, and the diameter of the 1st joints was 1.4 times the diameter of the FAB. Bonding was performed so as to double the size. The diameters of the 1st junction in two orthogonal directions were measured using a general-purpose electron microscope (manufactured by JEOL Ltd., JSM-6510LA). In all 100 FABs, if the difference in diameter between the two directions of the 1st joint is 2.5 μm or less, it is “A”; If there is even one 1st joint portion exceeding 5 μm, the roundness is low and it is considered unsuitable for fine pitch applications, so it was designated as “D”.

(8) Heat Cycle Test After bonding in a nitrogen gas atmosphere with the wire bonder used in (2) above, the epoxy resin-encapsulated semiconductor sample was evaluated using a commercially available thermal cycle tester. The temperature history was maintained at −40° C. for 60 minutes, then heated to 125° C. and maintained at this temperature for 60 minutes. Taking this as one cycle, 1000 cycles of the test were conducted. Electrical measurement was performed after the test to evaluate conduction. The number of wires evaluated was 500. If the defect rate is 1% or less, "A";"

(9) High temperature storage test (long-term reliability)
After bonding in a nitrogen gas atmosphere with the wire bonder used in (2) above, a semiconductor sample sealed with epoxy resin was prepared. A semiconductor sample prepared using a commercially available constant temperature bath was held at 175° C. for 1000 hours, and then subjected to electrical measurement to evaluate conductivity. The number of wires evaluated was 500. If the defect rate is 1% or less, "A";"

(10) Loop formation property In the wire bonder used in (2) above, the 1st joint and the 2nd joint are made to have the same height in a nitrogen gas atmosphere, and the loop length (the wire connecting the 1st joint and the 2nd joint The bonding was performed so that the length of the loop was 2 mm and the loop height was 200 μm. Observing the loop from directly above, the maximum value of the deviation between the wire center C and the straight line connecting the center of the 1st joint and the center of the 2nd joint (the point where the wire center C is farthest from the straight line in the wire radial direction The distance between the wire center C and the straight line at ) was measured. The number of wires evaluated was 500, and if the number of defective wires in which the wire center C deviated from the straight line by 20 μm or more is 5% or less of the entire evaluated wires, “A” is exceeded, and if it is more than 5% and 10% or less. It was rated as "B", and if it exceeded 10%, the loop could not be formed stably, so it was rated as "D".

(11) Comprehensive evaluation "A" for all "A", "B" for 1 to 3 "B", "C" for 4 or more "B", "D" for each evaluation " was designated as "D". In this evaluation, not only those with "A", but also those with "B" and "C", according to the usage conditions such as the case where there are no restrictions on the bonding conditions depending on the type of semiconductor element, the present invention. It can be used with its working effect.

The results are shown in Table 2, and in Examples 1 to 11, good results were obtained in all the above evaluations (1) to (11).

On the other hand, in Comparative Example 1, in which the total content of Bi and Cu exceeded 500 ppm by mass, FAB with high sphericity could not be formed. In Comparative Example 2, in which the In content exceeds 2.0% by mass, the evaluation of specific resistance and loop formability was "D". Comparative Example 3, in which the total content of Au and Pd is less than 0.005% by mass, was evaluated as "D" in the heat cycle test and the high temperature storage test. In Comparative Example 6, in which the total content of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce exceeded 500 mass ppm, the evaluation of specific resistance and FAB formation was "D". In Comparative Example 5, in which the total content of Au and Pd exceeded 2.0% by mass, the specific resistance was evaluated as "D". Comparative Example 6, in which the In content was less than 0.005% by mass, was evaluated as "D" in the high-temperature storage test. In Comparative Example 7 in which the total content of Bi and Cu was less than 5 ppm by mass, the evaluation of the shape of the 1st joint was "D".

In order to solve the above problems, the bonding wire of the present invention has an In content of 0.005% by mass or more and 1.1 % by mass or less, and a content of one or two elements selected from Au and Pd. The total content of 0.005% by mass or more and 2.0% by mass or less , containing Bi and Cu, and the total content of one or more elements selected from Bi and Cu is 10 mass ppm or more and 500 mass ppm Hereinafter, the total content of one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce is 0 mass ppm or more and 500 mass ppm or less. , and the balance is Ag.

In the bonding wire according to the present invention, the total content of one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce is 30 mass ppm or more It can be 500 mass ppm or less.

In the bonding wire according to the present invention, In relative to the total content of Au and Pd
can be 2.9 or less.

In the bonding wire according to the present invention, the HAZ length generated when fabricating a FAB having a size 2.0 times as large as the wire diameter of a wire having a wire diameter of 25 μm in a nitrogen gas atmosphere can be 100 μm or less.

Claims (8)

In content is 0.005% by mass or more and 2.0% by mass or less,
The total content of one or two elements selected from Au and Pd is 0.005% by mass or more and 2.0% by mass or less,
The total content of one or more elements selected from Bi and Cu is 5 mass ppm or more and 500 mass ppm or less,
The total content of one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce is 0 mass ppm or more and 500 mass ppm or less,
A bonding wire whose balance is Ag. The total content of one or more elements selected from the group consisting of Ca, Mg, Ge, Y, Nd, Sm, Gd, La and Ce is 10 mass ppm or more and 500 mass ppm or less. 2. The bonding wire according to 1. 3. The bonding wire according to claim 1, wherein the ratio of the content of In to the total content of Au and Pd is 5 or less. The bonding wire according to any one of claims 1 to 3, wherein the content of Bi and Cu is essential. 5. The HAZ length of 100 μm or less generated when fabricating an FAB having a size 2.0 times the wire diameter of a wire with a wire diameter of 25 μm in a nitrogen gas atmosphere is 100 μm or less. bonding wire. The ratio of the average crystal grain size in the area up to 30% of the wire diameter in the radial direction from the wire surface to the average crystal grain size in the area up to 30% of the wire diameter in the radial direction around the wire center is 0.5 or more. The bonding wire according to any one of claims 1 to 5, which is 5.0 or less. If a crystal that exists in the center of the wire and has a ratio of the length in the wire radial direction to the length in the wire longitudinal direction of 1/10 or less is defined as an elongated crystal grain, the above-mentioned The bonding wire according to any one of claims 1 to 5, wherein the area ratio of the elongated crystal grains is 40% or less. A semiconductor device using the bonding wire according to any one of claims 1 to 7

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